A process for the industrial production of dihydroxylated benzene derivatives, and in particular of vanillin, ethylvanillin or a derivative thereof, generates a certain number of effluents, especially including aqueous effluents comprising at least one aromatic organic compound and at least one sulfate salt.
The aqueous effluents from a process for producing dihydroxylated benzene derivatives, and in particular vanillin or ethylvanillin or a derivative thereof, may be purified by precipitating the sulfate salt(s), for example by lowering the temperature for crystallizing the sulfate salt(s) and separating the sulfate salt(s) from the effluents.
At the present time, the sulfate salts are generally not recovered. The industrial effluents still generally contain from 2% to 15% of sulfate salt. The existing processes need to be improved from an ecological and economic viewpoint.